Sculling support



Aug. 15, 1967 A. w. M CLAY, JR 3,335,439

SCULLING SUPPORT FIGZ INVENTOR ALEXANDER W. McCLAY, JR.

ATTORNEYS 1967 A. w. MCCLAY, JR 3,335,439

SCULLING SUPPORT Filed July 13, 1965 5 Sheets-Sheet 5 INVENTOR ALEXANDER W. McCLAY, JR.

3&4 W M w ATTORNEYS Aug 15, 1967 A. w. M CLAY, JR 3,335,439

SCULLING SUPPORT Filed July 13, 1965 5 Sheets-Sheet 4 INVENTOR ALEXANDER w. McCLAY,JR.

ATTORNEYS Aug. 15, 1967 A. w. MCCLAY, JR

SCULLING SUPPORT 5 Sheets-Sheet 5 Filed July 13, 1965 INVENTOR ALEXANDER w. McCLA JR.

United States Patent 3,335,439 SCULLING SUPPORT Alexander W. McClay, Jr., 29 W. Bank St., Petersburg, Va. 23803 Filed July 13, 1965, Ser. No. 471,512 13 Claims. (Cl. 9-26) This invention appertains to an improvement in supports for a manually operated propulsion means for small boats generally, and more specifically relates to apparatus for supporting a paddle such that an oscillation movement transmitted to the paddle, about the support, automatically causes a proper feathering movement therein, as in sculling.

A broad object of the present invention is to provide such a support wherein the proper feathering and pitch attitude can be readily selected and adjusted for particular circumstances.

Briefly, cooperative structure is provided which permits the paddle blade to travel through the water in a plane fixedly spaced from the boat. This type operation is considerably more efficient than the operation available with many prior devices wherein the centerline of the paddle blade actually describes a section of a vertical right conical surface, as it is caused to reciprocate behind the boat. Such an arcuate path results in the paddle blade being brought forward near the ends of each push and pull stroke, thereby decreasing the propulsion efiiciency. The improved type operation of the present invention will be referred to herein as planar type operation.

The paddle clamp is mounted for substantially universal movement relative to the boat to be propelled, i.e., pivotal movement in relation to first, second and third axes supported from the boat. For the planar type operation, these three axes are in mutual orthogonal relation.

Automatic feathering or sculling operation is available through the provision of spaced apart means for locating the paddle clamp in operative positions on opposite sides of its axis, for the push and pull strokes, respectively.

With the foregoing in mind, another object of this invention is to provide the means whereby adjustments may be made in the working angle at which the paddle enters the water to account for the varying slopes of the transoms on different craft, so that this planar motion of the paddle may be realized.

A further object of the invention is to provide adjustment means whereby the pitch angles of the paddle or oar blade may be adjusted for the particular transverse pitch of the boat caused by the over-weighting of one side of the boat by personnel or other equipment, the device being mounted in a laterally sloped position due to the crown of the transom, list of the boat or other reasons.

A still further object of the invention is to provide an apparatus of the type described wherein the desired movement transmitted or imparted to the paddle can be ac complished by an unskilled operator with the use of one arm, even though that operator may be in an awkward position and unable to observe the movement imparted.

Another object of the invention is to provide an improved sculling support which will positively secure an oar or paddle in a selected position, but which may be instantly released and adjusted when it is desired to alter the direction of thrust created by the opposing pitch angles of the blade.

A still further and important object of this invention is to provide a paddle support which, when removed from the boat, does not require any permanent or semi-permanent structures to be left on the boat or paddle. Prior art supports which require clamps to remain on the oar When not used with the support have a serious disadvantage in that the oar has other independent uses.

A further object of the invention is to provide a support means wherein the paddle is securely supported to the boat, substantially outside thereof, but in a position for instant use by the boat occupant.

A further feature and object of the invention is the provision of a sculling support enabling substantially universal movement of the paddle with respect to the boat through the provision of axis adjustability and orientating the structure enabling control of the blade track relative to the boat and direction of travel.

With the foregoing objects outlined, and with other objects in view, which will appear as the description proceeds, the invention consists in the novel features hereinafter described in detail, illustrated in the accompanying drawings and pointed out in the appended claims.

In the drawings:

FIG. 1 is a view in side elevation of one embodiment of a device in accordance with the present invention;

FIG. 2 is a view in end elevation of the structure of FIG. 1, with a part omitted for clarity and also showing in dotted outline the paddle clamp in operative positions for the push and pull strokes, respectively;

FIG. 3 is a view in side elevation of a portion of structure incorporatable into the embodiment of FIGS. 1, 2, 7 and 8;

FIG. 4 is a view in plan of the structure of FIG. 3;

FIGS. 5 and 6 illustrate the journal component used in the structure of FIGS. 3 and 4;

FIG. 7 is a view in side elevation of a further embodiment of a device in accordance with the invention; and,

FIG. 8 shows the structure of FIG. 7 in end elevation with one part omitted for clarity of illustration.

Referring now to the drawings and particularly to FIGS. 1 and 2, there is shown a base for the sculling device in the form of a pair of C-clamps 11 and 13, secured together in spaced apart relation by the cross member or spacer plate 15. This clamping structure is provided to afiix the sculling device to the transom or stern of a boat. Attached to the left hand surface (FIG. 1) of plate 15, and centrally thereof, is a second spacer plate 17 which serves to connect a sleeve 19 to the C-clamp assembly.

It may be seen in FIG. 1 that sleeve 19 is afiixed to the C-clamp base by central plate 17 at approximately a 45 angle with the clamping plate 15, to maintain an angular relationship between the sleeve 19 and the paddle axis approximating when used with transoms of average slope and with the paddle at a more or less typical dipping angle. It is these angles which are made adjustable in order that the device may yield its best efiiciency when the two aforementioned variables are net average or typical, as will be explained in connection with the description of FIGS. 3-6.

The sleeve 19 defines an axis about which the upper portion of the structure, including the paddle clamp 21, may revolve, because it rotatably receives a pin or yoke stem 25 which carries the yoke 27. A snap ring 29, or the equivalent, is provided on the lower end of stem 25 (FIG. 1) to secure the pin within the sleeve 19.

The upper ends of the yoke 27 carry an annular band member 31 which is suitably apcrtured to receive pin 33 so as to pivotally mount the band within the ends of the yoke 27. The latter structure is secured together by snap rings 35 and 37, or the like. Depending from the annular band 31 is an integral arcuate appendage 39. The position of the appendage 39, relative to the pin 33 forming the second axis is opposite thereto, being 90 therefrom around the annular band 31. The arcuate appendage 39 is slotted at 41 (FIG. 2) for a considerable length therealong to receive the bolt 43 (FIG. 1), which may be positioned at any point along the slot 41, by tightening the nuts 45 and 47, to serve as a stop limit device upon striking against the yoke 27 itself, or the sleeve 19, if desired. This limits the pivotal movement of the paddle clamp 21 about the second axis, defined by pin 33, in the direction of the boat. The structure, of course, performs the function of opposing the force of the water acting to draw the paddle underneath the boat, i.e. in a downward direction, thereby relieving the operator of this chore.

By suitable adjustment of the bolt 43 along the slot 41, the angular orientation of the paddle clamp relative to the first axis, that is pin 25 in sleeve 19, is set or determined. In the embodiment of the invention of FIGS. 1 and 2, such an adjustment allows varying angles of the paddle to the water with varyingly sloped transoms and consequently provides a convenient arrangement for accommodating various size operators for the least tiring (most eflicient) manipulation of the sculler. Nevertheless, it may be appreciated that the axis of sleeve 19 extends approximately normal to the axis of the paddle, when the latter, held by the paddle clamp 21, is dipped into the Water in normal operation.

Extending upwardly from the annular band 31 at points 90 from pin 33 are opposed cars 51 and 53. The upper extremities of the ears 51 and 53 are apertured to receive pin 55 adapted for rotation therein, being retained by the snap rings 57 and 59. The pin 55 serves as the third axis which is the pivot axis for the paddle clamp 21.

The paddle clamp comprises a pair of jaws or angle irons 61 and 63 (FIG. 2), hingedly mounted on the pin 55, to permit opening at their upper ends to receive a paddle for clamping. The iron 61 includes the spaced apart sleeves 61' and 61" which receive the pin 55. The other angle iron 63 includes the sleeve 63', also fixed on the pin 55 to provide the hinging action between these irons. This clamping assembly 21. is free to rock to and fro on the pin 55, and as a matter of fact is adapted to be located in spaced apart positions on opposite sides of the third axis (pin 55) for the push and pull strokes, respectively. This is effected through the journals in the ears 51 and 53 which receive the pin 55.

The inner surfaces of the angle irons or the clamp aws 61 and 63 are fitted with resilient liner pads 65 and 67 which serve to protect the paddle shaft against chafing and splintering, and also to provide resiliency in order that a toggle mechanism 6'9 may rigidly clamp and hold the paddle.

A hook or lug 71 is located along the top edge of the angle iron 61 to receive a loop 73 of the toggle 69. A yoke 75 uprises from angle iron 63, in opposed relation to log 71, to pivotally receive a threaded pin 77 so as to form an adjustable toggle acting clamping or lockuig mechanism. The retaining loop 73 may be released from the book 71 by merely swinging pin 77 counterclockwise (as seen in FIG. 2).

In operation, an oar or paddle shaft (not shown) s disposed between the angle irons 61 and 63 with its longitudinal axis substantially centered within these clamp jaws. The blade end of the paddle (not shown) extends toward the viewer in the FIG. 2 showing (or to the left of the sheet in the FIG. 1 showing) to be dipped into the water (also not shown). The degree of dipping may be set by controlling the limit position of the annular band 31 through adjustment of the nut 43. Thus, as a back and forth motion is imparted to the paddle handle, the paddle will oscillate about pin 25 (the first axis) and rock from side to side about pin 55 (the third axis).

A pair of lugs 81 and 83 are afiixed along the upper edge of the annular band 31, at positions approximately 180 apart to threadably receive, respectively, studs or screws 85 and 87 which carry rocker stops 89 and 91. It is these stops which define the respective push and pull positions for the clamp 21, as illustrated in dotted line. Since the stops 89 and 91 are independently adjustable, the pitch angles may be adjusted when desirable, the pitch angles being formed by the plane of the paddle blade when rotatable positioned in the clamp-stop positions, and a plane through the center line of the paddle and normal to a vertical plane through the center line of the boat.

Thus, as will be apparent to those skilled in the art, as the paddle retained in clamp 21 pivots about the axis of pin 25, the rocking motion thereby set up about pin 55 will position the blade in the water so that forward thrust is achieved in each stroke direction through the opposing blade surfaces deflecting the water rearwardly as the oar is moved thwartwise. It is this structure which provides the automatic feathering or sculling action.

The rocking motion about pin 55 is limited by the top surfaces of the resilient heads of studs 90 and 91 which are adjustable vertically, to determine the feathering angle of the blade and so adjusts the pitch angles thereof for optimum efliciency.

The real function of the arcuate appendage 39 and its bolt 43, when in contact with yoke 27, is to transfer the reaction of the forward thrust component, of the paddle blade, from the operators arm to the lock structure. The adjustable feature permits optimum setting for different operatorsall through a minimal cost sculling device capable of automatic feathering.

Of course, the entire showing of FIG. 1 would be canted to the left in actual use such that the C-clamp 11 would attach to a stern (not shown) a few degrees off from the vertical, thus making it apparent that the paddle (also not shown) held in clamp 21 would enter the water to the left or downward side of FIG. 1.

In review, it can be seen that between the point of attachment to the boat and the paddle clamp, there is a first axis (pin 25) of rotation more or less vertically disposed to the direction of travel, a second axis of rotation (pin 33), generally transversely disposed and normal to said first axis, and a third axis (pin 55) disposed generally longitudinally and normal to said second axis and more or less normal to said first axis, the latter location being dependent upon position of thrust abutment bolt 43.

The length of stroke is determined by the amount of rotation about the first axis, the working angle at which the paddle is received in the water is accomplished by the amount of rotation about the second axis, and the alternating pitch angles of the paddle blade is determined by the degree of rotation about the third axis. The opposing pitch angles desired in the blade of the paddle, of course, are varied by the rotatable position of the paddle about its longitudinal axis prior to securing the toggle latch assembly, and to the position, vertically, of stops 89 and 91.

The sculling device of FIGS. 1 and 2 is adapted for greater flexibility in adjustments for achieving maximum efiiciency through employment of the alternative arrangements set forth in FIGS. 3-6. Essentially, this arrangement permits adjustment between the sleeve 19 and the C-clamp assembly, including C-clamps 11 and 13, and in so doing, also changes the angular relationship between sleeve 19 and the paddle axis, assuming that the dip angle of the paddle remains constant. It can be shown graphically by means of force vectors, that as the angle between the axis of sleeve 19 and the paddle axle (measured on the inboard side of these two axes), is decreased from 90 to approximately 65 (axis of sleeve 19 approaching a horizontal position with a constant dip angle) there is an increase in the ratio of forward thrust to the applied force, and a further decrease in this angle begins to yield some decrease in this ratio. However, it can also be shown that as this angle increases (axis of sleeve 19 approaching a verticalwith a constant dip angle) that there is a rather sharp decrease in the above ratio showing that the proper angular relationship of the first and third axes is of substantial importance to the most advantageous use of the device. It follows, from the above, that the dip or working angle of the paddle must then be set by means of the tilt of the first axis. In FIGS. 1 and 2 and FIGS. 7 and 8 a mean or average tilt of this axis is fixed, or built into the device, for reasons of simplicity. FIGS. 3-6 set forth an alternate arrangement by means of which the first axis may be individually set for optimum results. The sleeve or journal 19 is formed with a transverse sleeve 19a which is adapted to receive a pin or bolt 20. The journal 19 is fixed to the C-clamp assembly through a pair of spaced apart spacer plates 17a and 17b (or may be one or the other of these plates, rather than both, and thus located identically to one or the other), which replace the single centrally disposed plate 17 of FIG. 1. These spacer plates are integral with or welded to the cross spacer plate 15 of the C-clamp assembly. A pair of nuts 22 and 23 are provided to compress the spacer plates 17a and 17b against the sleeve 190 at any position along the arcuate slot 24. This provides the means to maintain the right-angle relationship between the first axis represented by the sleeve 19 and the paddle axis so as to maintain the planar movement of the paddle axis regardless of the slope of the C-clamp assembly, which, of course, is dependent upon the slope of the transom.

Although the arcuate slot 24 is shown of limited length, it may of course extend in a depending manner to the horizontal, such that the sleeve 19 may extend in a horizontal direction from the C-clamp assembly to provide extreme adjustments.

With the foregoing arrangements, the travel of the paddle shaft in clamp 21 relative to the stern of the boat clamped by the C-clamp assembly may be made planar through adjustment between the C-clamp assembly and the first axis (sleeve 19) for the desired working angle, with the adjustment of the arcuate appendage 39 through positioning of the bolt 43 therealong, allowing a right angle relationship between the paddle axis and the first axls.

The embodiment of the invention disclosed in FIG. 7 and FIG. 8 is operative on the same principles as the embodiment of FIGS. 1 and 2, and also is subject to the modification of FIGS. 3-6. However, a different structural arrangement is provided to achieve the enumerated advantages. Since a great deal of the structure is identical to that previously described, such structure will bear the same numbers with the prime assigned thereto, and the following description will be substantially confined to the structural distinctions.

The C-clamp structure includes the C-clamps 11' and 13', and the spacer plates 15 and 17. The first axis is also identical, including the sleeve 19', stem 25' and retaining ring 29. However, afiixed to the upper end of the stem 25' is an arcuate appendage 39, slotted at 41, to which is affixed a sleeve 34. The second axis, in the form of pin 33, is insertably received by sleeve 34 integrally formed with or welded to the pin 25', and arcuate member 39'.

The paddle clamp structure 21' is identical in all respects, including the latching toggle arrangement 69' and its third axis pin 55'. However, the supporting structure from the first axis sleeve 19' to the third axis pin 55' is in the form of an upper yoke 51' and a lower yoke 27'. This structure may be symmetrical and may be integrally formed or welded together. The assembly consists of a spider having a pair of upwardly extending arms and a pair of downwardly extending arms in the form of yokes 51' and 27', respectively. The spider structure is carried by the second axis pin 33' being journalled thereon and in turn carries the paddle clamp by receiving and journalling the third axis in the form of pin 55'.

A lug 54 is centrally disposed and depending from the spider to act as a stop or limit for the nuts 45' and 47 which fix the bolt 43' at a selectable position along the slot 41 in the appendage 39'.

The abutting engagement of the stop 54 and upper nut 47' is pictured in FIG. 7, and it should be apparent that this abutting engagement precludes further counterclockwise rotation of the clamp 21' along with its third axis 55' about the second axis 33'. Obviously, the limited position of the third axis 55' relative to the second axis may be set by placing of the nut 43' to control the blade or working angle of the paddle (not shown) relative to the water, carried in the clamp 21'.

The studs or screws and 87' engage threaded apertures in the lower yoke 27 at spaced apart positions to serve, respectively, as supports for the clamp 21 for the push and pull strokes. The clamp jaws 61' and 63' abut against the stops 89 and 91' to establish the respective positions, as illustrated in the dotted outline of FIG. 8.

A comparison of the structures of FIG. 2 and FIG. 8 will show different stop limit positions for the clamp 21 (21) to illustrate the use of feather angles of different magnitudes.

It should be pointed out that it is within the principles of the invention to incorporate a pair of toggle mechanisms 69 or 69' near opposite ends of the clamps 21 or 21 in order to provide a more sturdy device. This is pointed out because most canoe paddles or oars have tapered shafts and it is desirable to employ clamps up to 6" in length to clamp these shafts. While the clamp may conform to the tapered shafts, nevertheless, when extreme forces are encountered, it is deemed best to employ a pair of toggle mechanisms to insure firm gripping of the shafts. Thus, it will be appreciated that while two embodiments, along with certain modifications, of the invention have been illustrated and described herein, other modifications will occur to those skilled in the art, and it is, accordingly, intended that the invention be limited only by the scope of the appended claims, wherein What is claimed is:

1. A sculling support for securing an oar to a boat comprising, in combination a base adapted for attachment to the stern of the boat; a U-shaped yoke; first pivot means pivotally mounting the yoke on the base for movement about a first axis; support means adapted to be carried by the yoke; second pivot means pivotally mounting the support means on the yoke for movement about a second axis normal to said first axis; a paddle clamp; third pivot means pivotally mounting the clamp on said support means for movement about a third axis normal to the second axis; an appendage depending from the support means; and, stop limit means carried by the appendage and adapted to abut against at least one of the yoke and first pivot means to limit the pivotal motion of the support means about the second axis in at least one direction.

2. The sculling device of claim 1, wherein said appendage arcuately depends from the support means to follow a path extending through the yoke when the support means is pivoted about the second axis.

3. The sculling device of claim 2, wherein the stop limit means is adapted for positioning along a certain part of the length of the arcuate appendage to provide adjustment of the degree of pivoting of the support means about the second axis to the limit position.

4. A support for securing an oa-r to a boat for sculling through push and pull strokes comprising, a base adapted for attachment to the stern of the boat; a U-sh-aped yoke including a centrally disposed stem; means afiixed to the base and adapted to receive the stem to mount the yoke for pivotal movement about a first axis through the stem; annular band means adapted to be carried by the yoke; pin means for securing the annular band means to the yoke for pivotal movement about a second axis through the pin means; a depending arcuate appendage integral with the band means and extending within the yoke, in proximity to the stem; stop limit means adapted to be afiixed to the appendage at positions therealong to abut the yoke and thereby limit the pivotal motion of the annular band means about the second axis; a paddle clamp; means mounting the paddle clamp from the annular band means for pivotal movement relative thereto about an axis normal to the second pivot means; and, means for establishing clamp-to-annular band spacing at separate spaced apart positions on opposite sides of the axis for the clamp, for the push and pull strokes, respectively.

5. A support for securing an oar to a boat for sculling, which provides for lateral swinging of the oar blade and automatic feathering through push and pull strokes, comprising a base adapted for attachment to the stern of a boat; sleeve means affixed to the base and adapted to provide pivotal movement about a first axis therethrough; a shaft adapted to fit within the sleeve; yoke and pin means carried by the shaft to provide pivotal movement about a second axis through the pin means normal to the first axis for the yoke means; a paddle clamp comprising two opposing jaws hingedly supported by the yoke means for pivotal movement about a third axis normal to the second pivot axis; means for limiting the degree of pivoting of the clamp around the second axis to set the angle between the axis of the oar and the first axis; and, means for establishing separate spaced apart positions on opposite sides of the third axis for the clamp for the push and pull strokes, respectively.

6. The support of claim 5, including adjustable means afiixing the sleeve means to the base to tilt the first axis and remaining portion of the support relative to the boat.

7. The support of claim 5, wherein the means for limiting the degree of pivoting of the paddle clamp about the second axis comprises an arcuate appendage extending through the yoke means; and, means carried by the appendage at a selectable position therealong to abut the yoke means in the limit position.

8. The support of claim 5, wherein the yoke means uprises from the shaft to space the pin means therefrom; including, a support journalled on the pin means for spacing the third axis means therefrom; and, the means for limiting the degree of pivoting of the clamp around the second axis comprises an arcuate depending appendage from the support means and stop limit means settable therealong for abutting engagement with one of the shaft and yoke means to limit said angle.

9. The support of claim 5, wherein the yoke means includes an upper yoke and a lower yoke; the lower yoke receiving the pin means carried by the shaft, and the upper yoke reeciving the third axis means in spaced apart relation thereto; said means for limiting the degree of pivoting of the clamp comprising an uprising arcuate appendage supported from the shaft and extending through the lower yoke; and, stop limit means settable along the arcuate appendage to engage the yoke means for fixing said angle.

10. A sculling support for securing an oar to a boat, for propelling the boat by means of sculling strokes in which the blade feathering, is accomplished automatically, comprising, in combination, a base adapted for attachment to the stern of a boat; on oar clamp; first pivot means for providing pivotal movement around a first axis lying in a plane substantially vertical and parallel to the center line of the boat, a double-yoke means, second pivot means for providing pivotal movement of the yoke means around a second axis normal to said first axis, third pivot means hingedly supporting each of a plurality of opposed oar clamp jaws directly forming a third axis normal to and offset from said second axis, to provide limited universal movement of said clamp relative to the boat; means for limiting the pivotal movement of the third pivot means about the second axis in a direction to determine the angle between the oar and the water whereby to and fro pivotal movement of the clamp about the third pivot means imparts forward movement to the boat.

11. A sculling support for securing an oar, or paddle, to a boat for propelling the boat, comprising in com-bination, a base adapted for attachment to the stern of a boat; a paddle clamp; a first pivot means defining a first pivot axis fixedly attached to said base and lying in a plane substantially vertical and parallel to the longitudinal center line of said boat; a universal joint bracket comprising upper and lower yokes oriented apart defining a second pivot means through the lower yoke extremities to make a second pivot axis substantially normal to the first pivot axis; a third pivot means through upper yoke extremities defining a third pivot axis substantially normal to and offset from the second pivot axis; said universal joint bracket being supported by the first pivot means to provide limited universal movement of the upper yoke and third pivot means and to provide limited transverse rocking motion of the paddle clamp in addition to universal movement of its axis; means for limiting the pivotal movement of the upper yoke about the second pivot means to determine the angle between the oar and the water whereby to and fro pivotal movement of the paddle clamp relative to the first pivot means together with rocking movement of the clamp about the third pivot means positions the oar blade to impart forward thrust to the boat.

12. The sculling device of claim 11 including an arcuate appendage means extending through the lower yoke of the universal joint bracket, stop means carried by the appendage for abutting engagement with the yoke to limit the pivotal movement of the third pivot means thereby determining the angle between the oar and the water.

13. The sculling device of claim 12, wherein the stop means carried by the appendage means is adapted for positioning along a certain part of the length thereof to provide adjustment of the degree of pivoting of the paddle clamp about the second axis to the limit position.

References Cited UNITED STATES PATENTS 3,191,203 6/1965 McClay 926 FOREIGN PATENTS 793,003 1/1936 France.

MILTON BUCHLER, Primary Examiner.

P. E. SAUBERER, Assistant Examiner. 

1. A SCULLING SUPPORT FOR SECURING AN OAR TO A BOAT COMPRISING, IN COMBINATION A BASE ADAPTED FOR ATTACHMENT TO THE STERN OF THE BOAT; A U-SHAPED YOKE; FIRST PIVOT MEANS PIVOTALLY MOUNTING THE YOKE ON THE BASE FOR MOVEMENT ABOUT A FIRST AXIS; SUPPORT MEANS ADAPTED TO BE CARRIED BY THE YOKE; SECOND PIVOT MEANS PIVOTALLY MOUNTING THE SUPPORT MEANS ON THE YOKE FOR MOVEMENT ABOUT A SECOND AXIS NORMAL TO SAID FIRST AXIS; A PADDLE CLAMP; THIRD PIVOT MEANS PIVOTALLY MOUNTING THE CLAMP ON SAID SUPPORT MEANS FOR MOVEMENT ABOUT A THIRD AXIS NORMAL TO THE SECOND AXIS; AN APPENDAGE DEPENDING FROM THE SUPPORT MEANS; AND, STOP LIMIT MEANS CARRIED BY THE APPENDAGE AND ADAPTED TO ABUT AGAINST AT LEAST ONE OF THE YOKE AND FIRST PIVOT MEANS TO LIMIT THE PIVOTAL MOTION OF THE SUPPORT MEANS ABOUT THE SECOND AXIS IN AT LEAST ONE DIRECTION. 